FEATURES: Fix a typo and use uniform capitalization for list items.
[paraslash.git] / daemon.c
1 /*
2 * Copyright (C) 1997-2008 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file daemon.c Some helpers for programs that detach from the console. */
8 #include "para.h"
9 #include "daemon.h"
10 #include <pwd.h>
11
12 /* getgrnam() */
13 #include <sys/types.h>
14 #include <grp.h>
15
16 #include "string.h"
17
18 /**
19 * Do the usual stuff to become a daemon.
20 *
21 * Fork, become session leader, dup fd 0, 1, 2 to /dev/null.
22 *
23 * \sa fork(2), setsid(2), dup(2).
24 */
25 void daemon_init(void)
26 {
27 pid_t pid;
28 int null;
29
30 PARA_INFO_LOG("daemonizing\n");
31 pid = fork();
32 if (pid < 0)
33 goto err;
34 if (pid)
35 exit(EXIT_SUCCESS); /* parent exits */
36 /* become session leader */
37 if (setsid() < 0)
38 goto err;
39 if (chdir("/") < 0)
40 goto err;
41 umask(0);
42 null = open("/dev/null", O_RDONLY);
43 if (null < 0)
44 goto err;
45 if (dup2(null, STDIN_FILENO) < 0)
46 goto err;
47 if (dup2(null, STDOUT_FILENO) < 0)
48 goto err;
49 if (dup2(null, STDERR_FILENO) < 0)
50 goto err;
51 close(null);
52 return;
53 err:
54 PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
55 exit(EXIT_FAILURE);
56 }
57
58 /**
59 * fopen() the given file in append mode.
60 *
61 * \param logfile_name The name of the file to open.
62 *
63 * \return Either calls exit() or returns a valid file handle.
64 */
65 FILE *open_log(const char *logfile_name)
66 {
67 FILE *logfile;
68
69 assert(logfile_name);
70 logfile = fopen(logfile_name, "a");
71 if (!logfile) {
72 PARA_EMERG_LOG("can not open %s: %s\n", logfile_name,
73 strerror(errno));
74 exit(EXIT_FAILURE);
75 }
76 setlinebuf(logfile);
77 return logfile;
78 }
79
80 /**
81 * Close the log file of the daemon.
82 *
83 * \param logfile The log file handle.
84 *
85 * It's OK to call this with logfile == \p NULL.
86 */
87 void close_log(FILE* logfile)
88 {
89 if (!logfile)
90 return;
91 PARA_INFO_LOG("closing logfile\n");
92 fclose(logfile);
93 }
94
95 /**
96 * Log the startup message containing the paraslash version.
97 */
98 void log_welcome(const char *whoami, int loglevel)
99 {
100 PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
101 whoami);
102 PARA_DEBUG_LOG("using loglevel %d\n", loglevel);
103 }
104
105 /**
106 * Give up superuser privileges.
107 *
108 * \param username The user to switch to.
109 * \param groupname The group to switch to.
110 *
111 * This function returns immediately if not invoked with EUID zero. Otherwise,
112 * it tries to obtain the GID of \a groupname and the UID of \a username. On
113 * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
114 * are all set accordingly. On errors, an appropriate message is logged and
115 * exit() is called to terminate the process.
116 *
117 * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
118 */
119 void para_drop_privileges(const char *username, const char *groupname)
120 {
121 struct passwd *p;
122 char *tmp;
123
124 if (geteuid())
125 return;
126 if (groupname) {
127 struct group *g = getgrnam(groupname);
128 if (!g) {
129 PARA_EMERG_LOG("failed to get group %s: %s\n",
130 groupname, strerror(errno));
131 exit(EXIT_FAILURE);
132 }
133 if (setgid(g->gr_gid) < 0) {
134 PARA_EMERG_LOG("failed to set group id %d: %s\n",
135 (int)g->gr_gid, strerror(errno));
136 exit(EXIT_FAILURE);
137 }
138 }
139 if (!username) {
140 PARA_EMERG_LOG("root privileges, but no user option given\n");
141 exit(EXIT_FAILURE);
142 }
143 tmp = para_strdup(username);
144 p = getpwnam(tmp);
145 free(tmp);
146 if (!p) {
147 PARA_EMERG_LOG("%s: no such user\n", username);
148 exit(EXIT_FAILURE);
149 }
150 PARA_INFO_LOG("dropping root privileges\n");
151 setuid(p->pw_uid);
152 PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
153 }
154
155 /**
156 * Set/get the server uptime.
157 *
158 * \param set_or_get Chose one of the two modes.
159 *
160 * This should be called at startup time with \a set_or_get equal to \p
161 * UPTIME_SET which sets the uptime to zero. Subsequent calls with \a
162 * set_or_get equal to \p UPTIME_GET return the uptime.
163
164 * \return Zero if called with \a set_or_get equal to \p UPTIME_SET, the number
165 * of seconds ellapsed since the last reset otherwise.
166 *
167 * \sa time(2), difftime(3).
168 */
169 time_t server_uptime(enum uptime set_or_get)
170 {
171 static time_t startuptime;
172 time_t now;
173 double diff;
174
175 if (set_or_get == UPTIME_SET) {
176 time(&startuptime);
177 return 0;
178 }
179 time(&now);
180 diff = difftime(now, startuptime);
181 return (time_t) diff;
182 }
183
184 /**
185 * Construct string containing uptime.
186 *
187 * \return A dynamically allocated string of the form "days:hours:minutes".
188 *
189 * \sa server_uptime.
190 */
191 __malloc char *uptime_str(void)
192 {
193 long t = server_uptime(UPTIME_GET);
194 return make_message("%li:%02li:%02li", t / 86400,
195 (t / 3600) % 24, (t / 60) % 60);
196 }